Carrier-current system



May 12, 1925. 1,537,255

J. MILLS CARRIER CURRENT SYSTEM Filed Dec. 28, 1920 /nvenfor: John Mil/5.

Patented May 12, 1925.

UNITED STATES 1,537,255 PATENT OFFlCE.

JOHN MILLS, OF WYOMING, NEW JERSEY, ASSIGNOR T WESTERN ELECTRIC COM- PANY, INCORPORATED, OFNEW YORK, N. Y., A CORPORATION OF NEW YORK.

CARRIER-CURRENT SYSTEM.

Application filed December 28, 1920. Serial No. 433,716.

To all whom it may concern:

Be it known that 1, JOHN MlLLS, acitizen of the United States, residing at Wyoming, in the county of Essex and State of New Jersey,'have invented certain new and useful Improvements in Carrier-Current Systems, of which the following is a full, clear, concise, and exact descriptionn This invention relatesto a carrier wave lltll'lSllllSSlOIl system having means for separately interconnecting corresponding carrier channels.

One object of this invention is to'devise means whereby any one of a multiplicity of carrier wave channels terminating at an intermediate station ,may be connected with any one of a number of other carrier channels terminating at said station.

Another object is to provide means whereby the corresponding frequency channels of any number of carrier lines may be interconnected at an intermediate or toll station.

These objects and others which will appear as the nature of the invention is set forth may-be accomplished by means of the arrangement described in the following specification and illustrated in the accompanying drawing in which. Fig. 1 shows an intermediate station having five carrier .transn'iissioir lines entering it, and Fig. 2

illustrates a toll station equipment.

Briefly described, this invention as shown in the accompanying drawing comprises an intermediate station having a multiplicity of carrier transmission lines entering it, upon each of which a number of carrier channels are adapted to be superimposed, a balanced transformer for connecting each line to incoming and outgoing paths, filters included in-the incoming path for separating the carrier frequencies and switching means, which may be cord circuits, for connccting the corresponding channels of any pair of lines entering said toll station.

In Fig. 1, the station apparatus for three lines is shown in some detail, whereas for the other two lines the disclosure is purely diagrammatic; but it is to be understood that all the lines are connected to the switch terminals in the manner illustrated for lines A. D and E at the top and bottom of this figure. The arrangement at the bottom of the figure shows two lines. one of which is provided'with two channels and the other with a single channel, and hence in the former case but two paths can be completed through the intermediate station and in the latter but one channel is available.

Referring to Fig. 1, the line A provided with three carrier channels, which for identification purposes are referred to as A A and'A is connected by a balanced transformer 1 to incoming and outgoing paths 2 and 3 respectively and a network 4 adapted to simulate the impedances of the line is associated with the balanced transformer. The incoming path 2 is connected through filters 5, 6 and 7, selective of the respective signal frequencies of the three channels, to terminals of respective jacks 8, 9 and 10. The leadsconnected to the respective terminals are provided with signal mechanisms 11, L2 and 13, diagrammatieally shown, each of which includes a detector of any wellknown type and the usual signal indicating means.

The outgoing path connects the midpoint of the balanced transformer with the secondary windlng of a transformer 14, which has associated with it a plurality of primanner similar to line A, the connecting means being diagrammatically indicated by H, F and T.

Line D having two carrier channels is shown connected by a balanced transformer 18, through filters 19 and 20 to the terminals 21, 22 and through a transformer 23 to the terminals 24 and 25, a network 26 being associated with the balanced transformer 18 to simulate the impedance of the line.

Line E has a single carrier channel and is connected to its terminals 27 and 28 in a manner similar to the other lines and a network 40 designed to balance the line is associated with it.

It is to be understood that each of the channels superimposed upon the different lines is provided with a si nal indicating device of the type hereinbefbre referred to and in a manner similar to that disclosed for line A.

The- (.01 responding channels of the dif ferent lines, that is, A, B, C and D; A,

B C and D and A B and E, are no respectively supplied with carrier currents of the same frequency in any well-known manner. Hence, the channels D and D of line D are designed to transmit the same pairs of jacks connected to the incoming and outgoing paths of each channel will preferably be mounted side by side and the cords may be separate as herein shown or a single cord having four wires and two sets of plugs may be used, but in either case their plug terminals will be arranged side by side.

So that, in the act of answering a call, the

operator will connect both cords to the incoming and outgoing paths of a channel.

The operators receiver is connected to a pair of flexible contacts 32 of the key 31 associated with which are a pair of station-v ary contacts 33 connected by the leads 34 to the cord 29. Contacts 32 are also connected by connectors 35 to a second pair of flexible contacts 36 which are adapted to cooperate with a'pair of stationary contacts 37 connected by the leads 38 to the cord 30. The

operator s transmitter is connected to apair 1 of flexible contacts 40 of the key 41 having cooperating stationary contacts 42 connected to the leads 38 by the wires 43. The flexible contacts 44 are designed to cooperate with the pair of stationary contacts 45 con nected to the leads 34. Contacts 40 and 44 are connected by the connectors 46.

In answering a call the operator inserts the plugs 8' and 15 in the jacks8 and 15 and throws her keys in the direction indicated by the arrow 47, and hence their plungers 31 and 41 in the opposite direction to actuate contacts 32 and 40 respectively.

The incoming signal currents will flow from 'thefplug 8' through the cord 29. leads 34,

well-known detectin contacts 33 to the contacts 32 which are connected to the receiver 51. The transmission circuit includes the contacts 40 and 42, leads 43, conductors 38, cord 30, and plug 15.

By reversing the position of the keys the operator may receive over the circuit including the plug F, cord 30, conductors 38, contacts 37, and 36 and connectors 35; and transmission is effected over the circuit including the connectors 46, contacts 44 and 45, conductors 48, leads 34, cords 29 and the plug T.

The operators set is provided with any h and modulating devices, diagrammatica 1y indicated at 49 and 50, so that she may communicate with the The plungers of distant stations, either for ringing or talk ing purposes.

The modulating apparatus 50 may include a plurality of generators one for each channel, though a single adjustable generator G will preferably be used, to supply carrier current toany of the channels, as well as a low frequency ringing source RS and a ing the generator any desired frequency adjustment. Four frequency adjustments f f f and f, are indicated, corresponding to respective carrier frequencies employed by the channels. I

The operation of the system will be clear from the following description. A call coming in over channel A energizes the signal indicator 11. The operator having plugged the cord terminals 8' and 15 into the jacks 8 and 15, and set the keys 31 and 41 as described above, may communicate with the distant station. \Ve will suppose that the A subscriber desires to be connected with channel B of line B. The operator inserts the other plugsF' and T of her cord circuit into the upper jacks of line B and communicates with the station or subscriber to Having adjusted the oscillator G of her set to supply a carrier frequency 7, corresponding to the second channel, the operator procceds as described with reference to channel A and communicates with subscriber A \Ve will suppose that this subscriber desires to communicate with the subscriber using the corresponding channel of line D. The operator, will then insert the other plugs of the cord which-she is using into the jacks 22 and 25, inform subscriber D that another subscriber desires to communicate with him. advise subscriber A that the line is ready and return her keys 31 and '41 to neutral position. p

By properly actuating thekey 31, the operator is enabled to supervise all connections, since with this key in one position she may listen to subscriber A and with this key in the reverse position'she may listen to subscriber B Obviously, a single key may be used to connect the operators receiver with C with channel A, B or D when desired.

Thus, it will be seen that .any channel of the several lines may-be connected to a corresponding channel of any otherline.

A single stationequipment is herein shown, but it is to be understood that a plurality of cords and a corresponding number of keys, each adapted to connect the ope'rators set with one of the cord circuits, will be uscd, and that by actuating the prop er keys the operators set may be connected to any desired cord circuit. a Vhile a system having five carrier transmission lines, some of which. have three signal channels, another two and a third one for connecting a toll station with a plurality of distant stations has been described, it is evident that in principlethere is no limit to the number of lines which may be associated with said intermediate station and that, within practical limits, any number of channels may be superimposed on each line.

Obviously, the transmission lines may be associated with the distant stations in any desired manner, that is to say, eachline may extend to a different station, a plurality of f distant stations may be associated with a single hne, a carrier channel being assigned to each, or several lines may be used .for communication between each of the distant stations and thetoll station, should traflic conditions'demand it.

From the preceding description it will be evident that this arrangement provides a carrier'current system of great flexibility, since any frequency channel of any system may be connected to the corresponding channel of any other system extending between the toll station and the distant stations. Moreover,

the operator at the toll station may commu-- ni'cate with any subscriber or station and may also supervise all connections.

Although this system is described as particularly adapted to a .carrier system in which each channel employs the same incomingand outgoing frequency, it may also be applied to a system in which each channel has a different incoming and outgoing frequency, provided each carrier fre u'ency in one'direction is always associate with a definite carrierfrequency in the opposite direction. Inthis case it would be impossible to connect together twoii' hannels having the same outgoing frequency with respect to the terminal stations.

The nvention 1s not, of course,l1m1ted to systems mwhrch the'carrier wave channels are superposed on a couductingline circuit, but applies equally well to systems employing any other type of medium for transmission of the carrier waves.

Certain specific details have been herein shown and described merely for the purpose of disclosing. the principles of the invention and it is to be understood that this invention is not limited to these specific features but only by the scope of theappended claims.

As will have been seen from the foregoing description and the drawing, the term F carrier wave channel or carrier channel, or equivalent expression, is used herein to designate the apparatus which is individual rather than common to the carrier waves.

'Thus there is a transmitting channel for each carrier wave at each point of the system from which t 'ansmission is to take place on the respective carrier wave. T here are also individual receiving channels for the waves at stations at which the waves are to be separately received. Channel branch is" ge neric to transmitting and receiving channel and designates a' circuit or connection which is appro iriated for separate and independent use by and in connection with a par-' ticular carrier wave.

\Vhat is claimed is:

1. A signaling system comprising a multiplicity of lines having a plurality of carrier current channels employing carrier currents of different frequencies superimposed on each line and means at an intermediate station for connecting any channel of one line with achannclof any other line.

2. A signaling system comprising a multiplicity of lines, a plurality of separate communication channels superposed on each line, employing corresponding carrier frequencies, and means at an intermediate station for interconnecting the corresponding frequency channels of any of said lines,

3, A signaling system comprising an intermediate station, a multiplicity of lines entering said station, a plurality of carrier current channels employing different carrier. frequencies superimposed on each line, individual channel branches at said station and means for connectingcorresponding channel branches at said station.

4. A signaling system comprising an in termediate station, a multiplicity of lines entering said intermediate station, a plurality of carrier current channels employing diflerent carrier frequencies superimosed on each line, individual channel iiranches at said station and switching means for connecting corresponding channel branches at said station.

5. A signaling system comprising. a toll station, a multiplicity of lines entering said station, a plurality of carrier current channels employing diflerent carrier frequencies superimposed on each line, balancing means at said station for connecting two-way transmission paths to each line, individual,

channel branches at said station and means for connecting the corresponding channel branches of said lines.

(3. A carrier current system for connecting a plurality of terminal stations through an intermediate station comprising an intermediate station, a plurality of lines between respective terminal stations and said intermediate station, a plurality of carrier channels employing different carrier frequencies superposed on each line and means at said intermediate station for interconnecting a channel of any of said lines from one terminal station with a channel of any line from another terminal station.

7. A carrier current system for connecting a plurality of terminal stations through an intermediate station, comprising an intermediate station, a plurality of lines between each terminal station and said inter mediate station, a lurality of carrierchannels employing di erent carrier frequencies superposed on each line and means at the intermediate station for interconnecting the corresponding channels of any of said ines.

8. A carrier current system for connecting a plurality of terminal stations through an intermediate station, comprising an intermediate station, a plurality of lines between each terminal station and said intermediate station, a plurality'of carrier channels employing different carrier frequencies superposed on each line andmeans at the intermediate station for interconnecting a channel of any of said lines. from one terminal station with a corresponding channel of any one of said lines from another terminal station.

9. A signaling system comprising a multiplicity of lines having a plurality of carrier current channels employing difi'erent carrier frequencies superimposed, on each line, individual means at an intermediate station for interconnecting pairs of said channels and supervising means at said station for the interconnected channels.

10. A signaling system comprising a multi'pilicity of lines, each providedwith a plura ity of separate communication channels of corresponding carrier frequencies, means at an intermediate station for interconnecting the channels of one of said lines and the corresponding frequency channels of other of said lines and m ians at said station. for

supervising any channel interconnection.

11. A carrier current system for connecting a plurality of terminalstations through an intermediate station comprising an intermediate station, a plurality of lines between respective terminal stations and said intermediate siation, means associated with each line for permitting a plurality of carrier channels employing difi'erent carrier frequency currents superposed on each line and means at said intermediate station for interconnecting channels .of each of said lines from one terminal station with channelsof any of said lines from the other terminal stations, and supervising means at said intermediate station.

12. A carrier current system for connecting a plurality of terminal stations through an intermediate station, comprising an intermediate station, a plurality of lines between each terminal station and said intermediate station, carrier channels employing different carrier frequencies superposed on each line, means at the intermediate station for interconnecting the corresponding channels of any of said lines and means at said station for supervising any channel connection.

13. In a carrier signalling system, an interconnecting station, respective carrier receiving channel and carrier transmitting channel terminals thereat, an interconnecting circuit for extending connection from a receiving channel terminal to a transmitting channel terminal, local apparatus including a carrier wave transmitter and receiver, and switching arrangements for operatively connecting said local apparatus to said interconnecting circuit.

14. In a carrier current system, carrier current lines each havin respective receivin channel and transmitting channel termmals, the channels of each line employing a plurality of different carrier frequencies, an interconnecting circuit for extending connection from a receiving channel terminal to a transmitting channel terminal, a local carrier current transmitter having a source of carrier currents, means for deriving from said source a carrier current of the carrier frequency of the transmitting channel to which connection is extended, and means to utilize the derived current for talking over the connected transmitting channel.

15. Ina carrier wave system, an inter connecting station, a plurality of receiving carrier channel terminals and a plurality of transmitting carrier channel terminals, the

receiving channels and the transmitting.

channels employing wave frequencies respectively corresponding, a pair of interconnecting cords for extending connection between a receiving channel terminal and a transmitting channel terminal and another connection between a receiving channel terminal and a transmitting channel terminal which are oppositely directed to the first receiving and transmitting channels, an operators set including carrier wave trans-' mittlng and receiving sets, and switching arrangements for connecting either the receiving set or the transmitting set to either cord circuit at will.

16. In a carrier wave signaling system, an interconnecting station, a plurality of incoming carrier channel terminals thereat employing carrier Waves of respective frequencies, a plurality of groups of outgoing carrier channel terminals at said station, the outgoing channels of each group employing carrier waves of respective frequencies, and interconnecting means for extending a conncction from any incoming carrier channel 

